Plain text: Created a new HTML to plain text converter

To centralise logic to be more consistent, and to have smarter logic
which avoids just following newline format from input, preventing
smushing HTML elements (like list elements) next to eachother

app/Activity/Models/Comment.php

@@ -9,6 +9,7 @@ use BookStack\Users\Models\HasCreatorAndUpdater;
 use BookStack\Users\Models\OwnableInterface;
 use BookStack\Util\HtmlContentFilter;
 use BookStack\Util\HtmlContentFilterConfig;
+use BookStack\Util\HtmlToPlainText;
 use Illuminate\Database\Eloquent\Builder;
 use Illuminate\Database\Eloquent\Factories\HasFactory;
 use Illuminate\Database\Eloquent\Relations\BelongsTo;
@@ -87,6 +88,12 @@ class Comment extends Model implements Loggable, OwnableInterface
         return $filter->filterString($this->html ?? '');
     }
 
+    public function getPlainText(): string
+    {
+        $converter = new HtmlToPlainText();
+        return $converter->convert($this->html ?? '');
+    }
+
     public function jointPermissions(): HasMany
     {
         return $this->hasMany(JointPermission::class, 'entity_id', 'commentable_id')

app/Activity/Notifications/Messages/CommentCreationNotification.php

@@ -24,7 +24,7 @@ class CommentCreationNotification extends BaseActivityNotification
             $locale->trans('notifications.detail_page_name') => new EntityLinkMessageLine($page),
             $locale->trans('notifications.detail_page_path') => $this->buildPagePathLine($page, $notifiable),
             $locale->trans('notifications.detail_commenter') => $this->user->name,
-            $locale->trans('notifications.detail_comment') => strip_tags($comment->html),
+            $locale->trans('notifications.detail_comment') => $comment->getPlainText(),
         ]);
 
         return $this->newMailMessage($locale)

app/Activity/Notifications/Messages/CommentMentionNotification.php

@@ -24,7 +24,7 @@ class CommentMentionNotification extends BaseActivityNotification
             $locale->trans('notifications.detail_page_name') => new EntityLinkMessageLine($page),
             $locale->trans('notifications.detail_page_path') => $this->buildPagePathLine($page, $notifiable),
             $locale->trans('notifications.detail_commenter') => $this->user->name,
-            $locale->trans('notifications.detail_comment') => strip_tags($comment->html),
+            $locale->trans('notifications.detail_comment') => $comment->getPlainText(),
         ]);
 
         return $this->newMailMessage($locale)

app/Entities/Repos/BaseRepo.php

@@ -16,6 +16,7 @@ use BookStack\References\ReferenceUpdater;
 use BookStack\Sorting\BookSorter;
 use BookStack\Uploads\ImageRepo;
 use BookStack\Util\HtmlDescriptionFilter;
+use BookStack\Util\HtmlToPlainText;
 use Illuminate\Http\UploadedFile;
 
 class BaseRepo
@@ -151,9 +152,10 @@ class BaseRepo
         }
 
         if (isset($input['description_html'])) {
+            $plainTextConverter = new HtmlToPlainText();
             $entity->descriptionInfo()->set(
                 HtmlDescriptionFilter::filterFromString($input['description_html']),
-                html_entity_decode(strip_tags($input['description_html']))
+                $plainTextConverter->convert($input['description_html']),
             );
         } else if (isset($input['description'])) {
             $entity->descriptionInfo()->set('', $input['description']);

app/Entities/Tools/PageContent.php

@@ -16,6 +16,7 @@ use BookStack\Users\Models\User;
 use BookStack\Util\HtmlContentFilter;
 use BookStack\Util\HtmlContentFilterConfig;
 use BookStack\Util\HtmlDocument;
+use BookStack\Util\HtmlToPlainText;
 use BookStack\Util\WebSafeMimeSniffer;
 use Closure;
 use DOMElement;
@@ -303,8 +304,8 @@ class PageContent
     public function toPlainText(): string
     {
         $html = $this->render(true);
-
-        return html_entity_decode(strip_tags($html));
+        $converter = new HtmlToPlainText();
+        return $converter->convert($html);
     }
 
     /**

app/Util/HtmlToPlainText.php

@@ -0,0 +1,47 @@
+<?php
+
+namespace BookStack\Util;
+
+class HtmlToPlainText
+{
+    /**
+     * Inline tags types where the content should not be put on a new line.
+     */
+    protected array $inlineTags = [
+        'a', 'b', 'i', 'u', 'strong', 'em', 'small', 'sup', 'sub', 'span', 'div',
+    ];
+
+    /**
+     * Convert the provided HTML to relatively clean plain text.
+     */
+    public function convert(string $html): string
+    {
+        $doc = new HtmlDocument($html);
+        $text = $this->nodeToText($doc->getBody());
+
+        // Remove repeated newlines
+        $text = preg_replace('/\n+/', "\n", $text);
+        // Remove leading/trailing whitespace
+        $text = trim($text);
+
+        return $text;
+    }
+
+    protected function nodeToText(\DOMNode $node): string
+    {
+        if ($node->nodeType === XML_TEXT_NODE) {
+            return $node->textContent;
+        }
+
+        $text = '';
+        if (!in_array($node->nodeName, $this->inlineTags)) {
+            $text .= "\n";
+        }
+
+        foreach ($node->childNodes as $childNode) {
+            $text .= $this->nodeToText($childNode);
+        }
+
+        return $text;
+    }
+}